The present invention relates to a material made with super-absorbent fibers which may be wrapped around a cable for the purpose of blocking water passage therethrough, and more particularly to such a material which is or includes a single layer nonwoven.
In recent years, a number of different moisture absorbent wrapping materials have been developed for the specific purpose of protecting power cables and telecommunication (telecom) cables against moisture. All of these wraps or tapes contain super-absorbent polymers which provides the water-blocking capacity. Such super-absorbing polymers are well known in a variety of different arts. The super-absorbent materials are preferably of acrylic, starch or cellulosic origin, although others may be used in place of or in conjunction therewith. In many instances, the absorbent wrap is a laminate formed of two or three layers of nonwovens or films (e.g., polyester) with one of these layers being made of a super-absorbent polymer, typically an intermediate layer with the super-absorbent polymer being in the form of a powder.
The known absorbent wraps have not proven to be entirely satisfactory. In particular, the conventional wraps are too thick for the smaller diameter cables (e.g., fiber optic cables of less than 12 mm O.D.), which preferably utilize a wrap having a thickness not in excess of two millimeters. The conventional wraps also pose a potential source of trouble during cable production due to "powdering" (that is, the loss of super-absorbent polymer powder from the laminate) and due to the limited peel strength of the laminates. Additionally, the swelling capacity of the super-absorbent polymers is limited due to the necessary cohesion of the various outer layers of the laminate.
The cable market, and especially the telecom cable market, requires ever thinner absorbent wraps, with ever improved absorbent properties (e.g., swelling speed and height) and with sufficient tensile strength and ease of handling for improved machineability on the various types of modern cable-manufacturing equipment.
Accordingly, it is an object of the present invention to provide a single layer nonwoven absorbent material having a thickness not more than 2 millimeters.
Another object is to provide such an absorbent material exhibiting a high swelling speed and height.
A further object is to provide such an absorbent material which, because it is a single layer nonwoven, is easy to handle on industrial cable-wrapping equipment.
It is also an object of the present invention to provide such an absorbent material having a high tensile strength enabling its use on conventional modern cable-wrapping equipment.
It is another object to provide a water-absorbent laminate made from such an absorbent material.